Primitive Version

src/de/steamwar/bungeecore/listeners/mods/CustomPacketHandler.java

@@ -0,0 +1,44 @@
+package de.steamwar.bungeecore.listeners.mods;
+
+import de.steamwar.bungeecore.BungeeCore;
+import de.steamwar.bungeecore.sql.Mod;
+import net.md_5.bungee.BungeeCord;
+import net.md_5.bungee.api.connection.ProxiedPlayer;
+import net.md_5.bungee.api.event.LoginEvent;
+import net.md_5.bungee.api.event.PreLoginEvent;
+import net.md_5.bungee.api.plugin.Event;
+import net.md_5.bungee.netty.ChannelWrapper;
+import net.md_5.bungee.netty.PacketHandler;
+import net.md_5.bungee.protocol.packet.LoginPayloadResponse;
+import org.apache.commons.lang3.ArrayUtils;
+import org.apache.commons.lang3.StringUtils;
+
+import java.util.Arrays;
+import java.util.LinkedList;
+import java.util.List;
+
+public class CustomPacketHandler extends PacketHandler {
+
+    private LoginEvent     event;
+    private ChannelWrapper wrapper;
+
+    public CustomPacketHandler(LoginEvent event, ChannelWrapper wrapper) {
+        this.event = event;
+        this.wrapper = wrapper;
+    }
+
+    @Override public String toString() {
+        return null;
+    }
+
+    public void handle(LoginPayloadResponse response){
+        if(response.getData() == null) {
+            System.out.println("Data is null with id: " + response.getId() + " , which means Client has no installed mods!");
+            event.completeIntent(BungeeCore.get());
+            return;
+        }
+        
+
+        event.completeIntent(BungeeCore.get());
+    }
+}

src/de/steamwar/bungeecore/listeners/mods/FMLPing.java

@@ -0,0 +1,48 @@
+package de.steamwar.bungeecore.listeners.mods;
+
+import net.md_5.bungee.api.ServerPing;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class FMLPing extends ServerPing {
+    private final ForgeData forgeData = new ForgeData();
+
+    public FMLPing(ServerPing existing) {
+        super(existing.getVersion(), existing.getPlayers(), existing.getDescriptionComponent(), existing.getFaviconObject());
+    }
+
+    private static class ForgeData {
+        private final List<ForgeChannel> channels = new ArrayList<>();
+        private final List<ForgeMod>     mods     = new ArrayList<>();
+        private final int fmlNetworkVersion = 2;
+
+        public ForgeData() {
+            channels.add(new ForgeChannel("minecraft:unregister"));
+            channels.add(new ForgeChannel("minecraft:register"));
+            channels.add(new ForgeChannel("fml:handshake"));
+            mods.add(new ForgeMod("minecraft", "1.15.2"));
+            mods.add(new ForgeMod("forge", "ANY"));
+        }
+
+        private static class ForgeChannel {
+            private final String res;
+            private final String version = "FML2";
+            private final boolean required = true;
+
+            private ForgeChannel(String res) {
+                this.res = res;
+            }
+        }
+
+        private static class ForgeMod {
+            private final String modId;
+            private final String modmarker;
+
+            private ForgeMod(String modId, String modmarker) {
+                this.modId = modId;
+                this.modmarker = modmarker;
+            }
+        }
+    }
+}

src/de/steamwar/bungeecore/listeners/mods/Forge.java

@@ -27,10 +27,17 @@ import io.netty.buffer.UnpooledByteBufAllocator;
 import net.md_5.bungee.api.ProxyServer;
 import net.md_5.bungee.api.connection.Connection;
 import net.md_5.bungee.api.connection.ProxiedPlayer;
+import net.md_5.bungee.api.event.LoginEvent;
 import net.md_5.bungee.api.event.PluginMessageEvent;
 import net.md_5.bungee.api.event.PostLoginEvent;
+import net.md_5.bungee.api.event.ProxyPingEvent;
+import net.md_5.bungee.connection.InitialHandler;
 import net.md_5.bungee.event.EventHandler;
+import net.md_5.bungee.netty.ChannelWrapper;
+import net.md_5.bungee.netty.HandlerBoss;
+import net.md_5.bungee.protocol.packet.LoginPayloadRequest;
 
+import java.lang.reflect.Field;
 import java.nio.charset.StandardCharsets;
 import java.util.*;
 import java.util.concurrent.TimeUnit;
@@ -39,6 +46,7 @@ public class Forge extends BasicListener {
 
     private static final String FMLHS = "FML|HS";
     private static final String FMLHS13 = "fml:handshake";
+    private static final String WRAPPER = "fml:loginwrapper";
     private static final byte[] REGISTER;
     private static final byte[] REGISTER13;
     private static final byte[] HELLO = new byte[]{0, 2, 0, 0, 0, 0};
@@ -58,6 +66,36 @@ public class Forge extends BasicListener {
         buf.readBytes(REGISTER13);
     }
 
+    @EventHandler
+    public void onServerConnected(LoginEvent event){
+        //Wir senden Packet ID 1
+        //Wir wollen empfangen Packet ID 2
+        //(FMLHS13, new byte[]{4, 1, 0, 0, 0});
+        //13,102,109,108,58,104,97,110,100,115,104,97,107,101 = 13 + "fml:handshake"
+        event.getConnection().unsafe().sendPacket(new LoginPayloadRequest(1,WRAPPER, new byte[]{13,102,109,108,58,104,97,110,100,115,104,97,107,101,4,1,0,0,0}));
+        event.registerIntent(BungeeCore.get());
+
+
+        InitialHandler handler = (InitialHandler) event.getConnection();
+
+        Field ch;
+        ChannelWrapper wrapper = null;
+
+        try{
+            ch = handler.getClass().getDeclaredField("ch");
+            ch.setAccessible(true);
+            wrapper = (ChannelWrapper) ch.get(handler);
+        } catch (NoSuchFieldException | IllegalAccessException e) {
+            e.printStackTrace();
+        }
+        wrapper.getHandle().pipeline().get(HandlerBoss.class).setHandler(new CustomPacketHandler(event, wrapper));
+    }
+
+    @EventHandler
+    public void onServerPing(ProxyPingEvent event) {
+        event.setResponse(new FMLPing(event.getResponse()));
+    }
+
     @EventHandler
     public void onPostLogin(PostLoginEvent event) {
         ProxiedPlayer player = event.getPlayer();